Protective Net for Sports, and Protective Net for Golf, Protective Net for Soccer, Protective Net for Baseball, Protective Net for Tennis, and Protective Net for Volleyball Using the Same

ABSTRACT

The present invention forms meshes between intersections of synthetic fiber cords while the synthetic fiber cords having a form in which a plurality of synthetic fiber filaments are plied and twisted is crossed in a knotless type, wherein a diameter (d) of the synthetic fiber cord satisfies the Equation (I), a maximum distance (DI) between the intersections adjacent to each other satisfies the Equation (II), and a minimum distance (D2) between the intersections adjacent to each other satisfies the Equation (III).Since the present invention is made lightweight with a lower areal density than a conventional protective net for sports and increases rate of hole size with a small diameter of the synthetic fiber cord constituting the protective net, the present invention improves resistance against wind during manufacture of a protective net structure, and has excellent mechanical properties and thus provides excellent resistance against impact applied when a ball flies and bumps. Consequently, the present invention minimizes damage and extends a replacement cycle.Further, the present invention improves visibility with the high rate of hole size, and also improves stability by effectively preventing penetration of the ball between the meshes.Further, the present invention is easily mounted in the protective net structure and provides excellent flame retardancy and weather resistance.

TECHNICAL FIELD

The present invention relates to a protective net for sports that isinstalled in golf courses, a baseball field, or the like to prevent ahit golf ball or baseball from escaping out of the protective net, andto a protective net for golf, a protective net for soccer, a protectivenet for baseball, a protective net for tennis, and a protective net forvolleyball using the same. More particularly, the present inventionrelates to a protective net for sports which is made lightweight, hasexcellent resistance against wind, provides excellent impact resistance,extends a replacement cycle, has excellent visibility with a high rateof hole size, effectively prevents a golf ball, a baseball, or the likefrom penetrating out of the protective net, and has an improvedstability, excellent flame retardancy and weather resistance, and to aprotective net for golf, a protective net for soccer, a protective netfor baseball, a protective net for tennis, and a protective net forvolleyball using the same.

BACKGROUND ART

Protective nets for sports are installed in a golf course or baseballfield and are used to prevent hit golf balls or baseballs, etc. fromescaping out of the protective nets.

As a conventional protective net for sports, a protective net for sportswhich forms meshes between intersections of high-density polyethylene(hereinafter, referred to as “HDPE”) cords while the HDPE cords having aform in which a plurality HDPE filaments are plied and twisted arecrossed in a knot type or a knotless type, is mainly used.

However, the conventional protective net for sports had to set adiameter of the HDPE cords to be thicker than at least 1.8 mm in orderto achieve a desired level of impact resistance and abrasion resistance,whereby the protective net for sports has a high areal density and aweakness of windage resistance, so that there were problems that it iseasily damaged by the wind after being installed, and a lot of time andmanpower are required to remove the protective net.

Further, the conventional protective net for sports is easily damagedbecause of having low resistance to impact applied when the hit golfball flies and bumps against the protective net, and has a low rate ofhole size, which is calculated by dividing the area A of FIG. 3 by thearea B of FIG. 3 and then multiplying it by 100, and thus, there is aproblem that the visibility is also deteriorated.

In addition, the conventional protective net for sports has a problemthat flame retardancy and weather resistance are deteriorated.

DETAILED DESCRIPTION OF THE INVENTION [Technical Problem]

An object of the present invention is to provide a protective net forsports which is made lightweight, has excellent resistance against wind,provides excellent impact resistance, extends a replacement cycle, hasexcellent visibility with a high rate of hole size, effectively preventsa golf ball, a baseball, or the like from penetrating out of theprotective net, and thus has an improved stability, excellent flameretardancy and weather resistance, and a protective net for golf, aprotective net for soccer, a protective net for baseball, a protectivenet for tennis, and a protective net for volleyball using the same.

[Technical Solution]

In order to achieve the above object, there is provided a protective netfor sports which forms meshes between intersections of synthetic fibercords while the synthetic fiber cords having a form in which a pluralityof synthetic fiber filaments are plied and twisted are crossed in aknotless type, wherein a diameter (d) of the synthetic fiber cordsatisfies the following Equation (I), a maximum distance (D1) betweenthe intersections adjacent to each other satisfies the followingEquation (II), and a minimum distance (D2) between the intersectionsadjacent to each other satisfies the following Equation (III):

$\begin{matrix}{{{Diameter}\mspace{14mu}(d)\mspace{14mu}{of}\mspace{14mu}{synthetic}\mspace{14mu}{fiber}\mspace{14mu}{cord}} = {N \times \sqrt{\frac{m \times {\sin^{2}(0)} \times \frac{1}{2}\left( {v_{0}^{2} - {9.81 \times h}} \right)}{\sigma \times ɛ \times L \times \pi}}}} & I \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 1} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = \frac{\pi\; R}{2\left( {1 + ɛ} \right)}} & {II} \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 2} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = {\frac{\pi\; R}{2\left( {1 + ɛ} \right)} \times \left( \frac{n}{n + 4} \right)}} & {III}\end{matrix}$

In the Equations (I), (II) and (III), the units of each of the diameter(d) of the synthetic fiber cord, the maximum distance (D1) and theminimum distance (D2) between intersections adjacent to each other aremm, m is a mass of a ball, N is a constant of 14.14214, c is an strainof the synthetic fiber filament material, θ is ball hitting angle, σ isa stress of the synthetic fiber filament material, Vo is a maximumvelocity of a hit ball, L is a total length of a net bumped by the hitball, which is calculated by the following Equation (IV), h is a heightof the net that receives impact by the hit ball, which is calculated bythe following Equation (V), R is a radius of the ball to which hit isapplied, and n is the number of twists applied to the synthetic fiberfilament to prepare the synthetic fiber cord;

L=12.007×N2×√{square root over (N1)}  (IV)

In the above Equation (IV), N2 is an integer of 12, 17 or 24 as thenumber of distances (D) between the intersections of the net thatreceives impact by the hit ball, and N1 is an integer of 1,2 or 4 as thenumber of intersections of the synthetic fiber cords to which the impactis applied by the ball;

$\begin{matrix}{h = \frac{\left( {{Vo} \times \sin\; 0} \right)^{2}}{2 \times 9.81}} & (V)\end{matrix}$

in the Equation (V), Vo is an initial velocity of the hit ball, and θ isa ball hitting angle.

In the Equation (IV), N2 may be obtained by a maximum value and aminimum value of the diameter (d) of the synthetic fiber cord of theEquation (I), based on the number of distances (D) between theintersections of the net that receives impact by the hit ball.

[ADVANTAGEOUS EFFECTS]

Since the present invention is made lightweight with a lower arealdensity than a conventional protective net for sports and increases rateof hole size with a small diameter of the synthetic fiber cordconstituting the protective net, the present invention improvesresistance against wind during manufacture of a protective netstructure, and has excellent mechanical properties and thus providesexcellent resistance against impact applied when a ball flies and bumps.Consequently, the present invention minimizes damage and extends areplacement cycle.

Further, the present invention improves visibility with the high rate ofhole size, and also improves stability by effectively preventingpenetration of the ball between the meshes.

Further, the present invention is easily mounted in the protective netstructure and provides excellent flame retardancy and weatherresistance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a part of a protective net for sports.

FIG. 2 is an enlarged photograph showing an intersection (X) of thesynthetic fiber cord (C) in FIG. 1.

FIG. 3 is a schematic diagram showing an area A and an area B used forcalculating a rate of hole size.

FIGS. 4 to 6 are schematic diagrams showing the number (N2) of distances(D) between intersections of a protective net that receives impact by aball according to a position where the ball is bumped against theprotective net.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, the present invention will be described in detail throughthe accompanying drawings.

As shown in FIGS. 1 and 2, the protective net for sports according tothe present invention is characterized by forming meshes betweenintersections of synthetic fiber cords while the synthetic fiber cordsin which a plurality of synthetic fiber filaments are plied and twistedare crossed in a knotless type, wherein a diameter (d) of the syntheticfiber cord satisfies the following Equation (I), a maximum distance (D1)between the intersections adjacent to each other satisfies the followingEquation (II), and a minimum distance (D2) between the intersectionsadjacent to each other satisfies the following Equation (III):

$\begin{matrix}{{{Diameter}\mspace{14mu}(d)\mspace{14mu}{of}\mspace{14mu}{synthetic}\mspace{14mu}{fiber}\mspace{14mu}{cord}} = {N \times \sqrt{\frac{m \times {\sin^{2}(0)} \times \frac{1}{2}\left( {v_{0}^{2} - {9.81 \times h}} \right)}{\sigma \times ɛ \times L \times \pi}}}} & I \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 1} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = \frac{\pi\; R}{2\left( {1 + ɛ} \right)}} & {II} \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 2} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = {\frac{\pi\; R}{2\left( {1 + ɛ} \right)} \times \left( \frac{n}{n + 4} \right)}} & {III}\end{matrix}$

in the Equations (I), (II) and (III), the units of each of the diameter(d) of the synthetic fiber cord, the maximum distance (D1) and theminimum distance (D2) between the intersections adjacent to each otherare mm, m is a mass of a ball, N is a constant of 14.14214, c is anstrain of the synthetic fiber filament material, θ is ball hittingangle, σ is a stress of the synthetic fiber filament material, Vo is amaximum velocity of a hit ball, L is a total length of a net bumped bythe hit ball, which is calculated by the following Equation (IV), h is aheight of the net that receives impact by the hit ball, which iscalculated by the following Equation (V), R is a radius of the ball towhich hit is applied, and n is the number of twists applied to thesynthetic fiber filament to prepare the synthetic fiber cord,

L=12.007×N2×√{square root over (N1)}  (IV)

in the Equation (IV), N2 is an integer of 12, 17 or 24 as the number ofdistances (D) between the intersections of the net that receives impactby the hit ball, and N1 is an integer of 1,2 or 4 as the number ofintersections of the synthetic fiber cords to which the impact isapplied by the ball,

$\begin{matrix}{h = \frac{\left( {{Vo} \times \sin\; 0} \right)^{2}}{2 \times 9.81}} & (V)\end{matrix}$

in the Equation (V), Vo is an initial velocity of the hit ball, and θ isa ball hitting angle.

The number (N2) of the distances (D) between the intersections whichreceive impact by the hit ball is determined depending on a positionwhere the ball bumps against the protective net as shown in FIGS. 4 to6.

Specifically, when the ball bumps against the position of the protectivenet shown in FIG. 4, the number (N2) of the distances (D) between theintersections which receive impact by the hit ball becomes 12, and thenumber (N1) of intersections which receive impact by the hit ballbecomes 1.

On the other hand, when the ball bumps against the position of theprotective net shown in FIG. 5, the number (N2) of the distances (D)between the intersections which receive impact by the hit ball becomes17, and the number (N1) of intersections which receive impact by the hitball becomes 2.

On the other hand, when the ball bumps against the position of theprotective net shown in FIG. 6, the number (N2) of the distances (D)between the intersections becomes 24, and the number (N1) ofintersections which receive impact by the hit ball becomes 4.

The protective net for sports of the present invention may be used as aprotective net for golf, a protective net for soccer, a protective netfor baseball, a protective net for tennis, a protective net forvolleyball, or the like.

As the synthetic fiber filament constituting the synthetic fiber cord,an aramid filament may be used alone, or the aramid filament and othersynthetic fiber filament except the aramid filament may be used in acombination with each other.

If the present invention uses the protective net for golf in which thesynthetic fiber cord is an aramid cord consisting of the aramidfilament, it is preferred that a diameter (d) of the aramid cord is 0.85mm to 1.5 mm, a maximum distance (D1) of the intersections adjacent toeach other is 35 mm or less, and a minimum distance (D2) of theintersections adjacent to each other is 20 mm or more.

If the present invention uses the protective net for soccer in which thesynthetic fiber cord is an aramid cord consisting of the aramidfilament, it is preferred that a diameter (d) of the aramid cord is 0.59mm to 0.84 mm, a maximum distance (D1) of the intersections adjacent toeach other is 140 mm or less, and a minimum distance (D2) of theintersections adjacent to each other is 130 mm or more.

If the present invention uses the protective net for baseball in whichthe synthetic fiber cord is an aramid cord consisting of the aramidfilament, it is preferred that a diameter (d) of the aramid cord is 0.75mm to 1.07 mm, a maximum distance (D1) of the intersections adjacent toeach other is 50 mm or less, and a minimum distance (D2) of theintersections adjacent to each other is 40 mm or more.

If the present invention uses the synthetic fiber cord as the protectivenet for tennis, it is preferred that a diameter (d) of the syntheticfiber cord is 0.73 mm to 1.03 mm, a maximum distance (D1) of theintersections adjacent to each other is 42 mm or less, and a minimumdistance (D2) of the intersections adjacent to each other is 38 mm ormore.

If the present invention uses the synthetic fiber cord as the protectivenet for volleyball, it is preferred that a diameter (d) of the syntheticfiber cord is 0.33 mm to 0.47 mm, a maximum distance (D1) of theintersections adjacent to each other is 126 mm or less, and a minimumdistance (D2) of the intersections adjacent to each other is 122 mm ormore.

When the diameter (d) of the synthetic fiber cord is lower than theabove range, the mechanical properties such as a tensile strength and anabrasion resistance of the synthetic fiber cord are deteriorated, andthus, there is highly likely that the protective net for sports iseasily damaged by an impact applied when the hit golf ball or baseballball flies and bumps against the protective net, whereas when thediameter (d) of the synthetic fiber cord exceeds the above range, sincea areal density of the protective net for sports becomes heavier than180 g/m² and the dimeter of the protective net diameter increases, aresistance to external environments such as wind and typhoons isreduced, which increases a likelihood that the installed protective netis easily damaged, and a rate of hole size of the protective net forsports is lowered to less than 88%, making viewing of the gameuncomfortable.

If the distance between the intersections (X) of the synthetic fibercords exceeds the above range, there is a problem that a protectivefunction of the protective net for sports is deteriorated due topenetration of a golf ball or a baseball through a mesh of theprotective net for sports. If it is less than the above range, the meshis formed too small, making viewing of the game uncomfortable.

That is, the protective net for sports according to the presentinvention wherein the diameter (d) of the synthetic fiber cord is 0.85mm to 1.5 mm, the maximum distance (D1) of the intersections adjacent toeach other is 35 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 20 mm or more, can be used asthe protective net for golf.

Further, the protective net for sports according to the presentinvention wherein the diameter (d) of the synthetic fiber cord is 0.59mm to 0.84 mm, the maximum distance (D1) of the intersections adjacentto each other is 140 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 135 mm or more can be used asthe protective net for soccer.

Further, the protective net for sports according to the presentinvention wherein the diameter (d) of the synthetic fiber cord is 0.75mm to 1.07 mm, the maximum distance (D1) of the intersections adjacentto each other is 50 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 40 mm or more can be used theprotective net for baseball.

Further, the protective net for sports according to the presentinvention wherein the diameter (d) of the synthetic fiber cord is 0.73mm to 1.03 mm, the maximum distance (D1) of the intersections adjacentto each other is 42 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 38 mm or more can be used as theprotective net for tennis.

Further, the protective net for sports according to the presentinvention wherein the diameter (d) of the synthetic fiber cord is 0.33mm to 0.47 mm, the maximum distance (D1) of the intersections adjacentto each other is 126 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 122 mm or more can be used asthe protective net for volleyball.

The aramid cord (C) consists of two strands and three or less strands ofaramid filaments having a fineness of preferably 1,200 denier to 5,000denier, more preferably 2,000 to 5,000 denier, and an strain of thearamid filament is preferably 2% or more and 4% or less.

Those in which a resin containing an ultraviolet stabilizer is coatedonto the synthetic fiber cord are more preferable for improving aweather resistance.

The protective net for sports of the present invention has a cuttingstrength of 114 daN or more, or 114 daN to 120 daN, and may beconfigured to sew a fabric having a narrow width at an end of theprotective net for sports to improve mounting during installation.

As one embodiment, in order to prevent all loosening of the protectivenet of a Knotless type when cutting or installing the protective net, afine fabric is sewn at the end of the protective net.

As another embodiment, in order to easily hang or mount the protectivenet on a post for installation of the protective net, a metal ring-typedjig may be installed when sewing the fine fabric at the end of theprotective net.

As still another embodiment, when Velcro is attached to the post forinstallation of the protective net, in order to improve attachabilityand detachability of the protective net, the Velcro may be sewn togetherwhen stitching the fine fabric at the end of the protective net.

The present invention is made lightweight with a lower areal densitythan a conventional protective net for sports, and a diameter of thesynthetic fiber cord constituting the protective net is considerablysmaller than a diameter of the conventional HDPE cord which leads to anincrease in a rate of hole size. Therefore, the present inventionimproves resistance against wind during manufacture of a protective netstructure, and has excellent mechanical properties and thus providesexcellent resistance against impact applied when a golf ball or abaseball ball flies and bumps. Consequently, the present inventionminimizes damage and extends a replacement cycle.

Specifically, the rate of hole size of the protective net for sports maybe 90% or more, 90% to 100%, or 90% to 99.5%, according to the followingEquation (VI):

$\begin{matrix}{{{Rate}\mspace{14mu}{of}\mspace{14mu}{hole}\mspace{14mu}{size}} = {\left( \frac{A}{B} \right) \times 100}} & ({VI})\end{matrix}$

in the Equation (VI), A is an area of the mesh, and B is an areaobtained by multiplying a value (l1) adding a diameter (d) of the aramidcord to a transverse length (l2) of the mesh, and a value (h1) addingthe diameter (d) of the aramid cord to a longitudinal length (h2) of themesh. Further, an abrasion resistance may be 20 minutes or more, or 20minutes to 35 minutes, wherein the abrasion resistance is a timerequired to damage the protective net by allowing a golf ball rotatingat 3,000 rpm to contact the same position of the protective net aftermounting the protective net to a rotational friction tester.

Further, a areal density of the protective net for sports may be 1 g/m²to 100 g/m², or 5 g/m² to 80 g/m².

Furthermore, the protective net for sports of the present invention alsocan improve a stability by effectively preventing a golf ball or abaseball ball from penetrating between the meshes, while enhancing avisibility due to the high rate of hole size.

Still furthermore, the protective net for sports of the presentinvention can be easily mounted on a structure of the protective net,and has an excellent flame retardancy and a weather resistance.

Hereinafter, the present invention will be described in more detail byway of examples and comparative examples.

However, the protection scope of the present invention should not beinterpreted as being limited only to these examples.

EXAMPLE 1

Two strands of aramid filaments having an strain of 3% and a fineness of4,500 denier were plied and twisted to prepare aramid cords having adiameter (d) of 0.95 mm.

Next, meshes were formed while crossing the aramid cords in a knotlesstype as shown in FIGS. 1 and 2, thereby manufacturing a protective netfor golf.

In this case, an distance between the intersections (X) of the aramidcords was adjusted to 25 mm.

The results of evaluating a cutting strength, a areal density, a rate ofhole size, and an abrasion resistance of the manufactured protective netfor golf were shown in Table 1.

Comparative Example 1

Two strands of aramid filaments having a fineness of 3,000 denier wereplied and twisted to prepare aramid cords having a diameter (d) of 0.8mm.

Next, meshes were formed while crossing the aramid cords in a knotlesstype as shown in FIGS. 1 and 2 to manufacture a protective net for golf.

In this case, an distance between the intersections (X) of the aramidcords was adjusted to 23 mm.

Comparative Example 2

Five strands of high-density polyethylene (HDPE) filaments having afineness of 3,000 denier were plied and twisted to prepare HDPE cordshaving a diameter (d) of 1.40 mm.

Next, meshes were formed while crossing the HDPE cords in a knotlesstype as shown in FIGS. 1 and 2 to manufacture a protective net for golf.

In this case, an distance between the intersections (X) of the HDPEchodes was adjusted to 23 mm.

The results of evaluating a cutting strength, a areal density, a rate ofhole size, and an abrasion resistance of the manufactured protective netfor golf were shown in Table 1.

TABLE 1 Comparative Comparative Category Example 1 Example 1 Example 2Equation(I) Maximum  1.06 mm  1.03 mm  1.94 mm value Minimum  0.95 mm 0.92 mm  1.72 mm value Equation(II) 32.42 mm 32.42 mm 29.64 mmEquation(III) 25.01 mm 25.01 mm 22.86 mm Cutting strength(daN) 114 11371 Rate of hole size(%) 92.2 94.5 86.1 Areal density(g/m²) 66 52 120Abrasion resistance(hour) 31(Unbroken) 17 17

In Table 1 above, the values of Equation (I), Equation (II) and Equation(III) are as follows.

$\begin{matrix}{{{Diameter}\mspace{14mu}(d)\mspace{14mu}{of}\mspace{14mu}{synthetic}\mspace{14mu}{fiber}\mspace{14mu}{cord}} = {N \times \sqrt{\frac{m \times {\sin^{2}(0)} \times \frac{1}{2}\left( {v_{0}^{2} - {9.81 \times h}} \right)}{\sigma \times ɛ \times L \times \pi}}}} & I \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 1} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = \frac{\pi\; R}{2\left( {1 + ɛ} \right)}} & {II} \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 2} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = {\frac{\pi\; R}{2\left( {1 + ɛ} \right)} \times \left( \frac{n}{n + 4} \right)}} & {III}\end{matrix}$

In the Equations (I), (II) and (III), the units of each of the diameter(d) of the synthetic fiber cord, the maximum distance (D1) and theminimum distance (D2) between the intersections adjacent to each otherare mm, m is a mass of a ball, N is a constant of 14.14214, c is anstrain of the synthetic fiber filament material, θ is a ball hittingangle, σ is a stress of the synthetic fiber filament material, Vo is amaximum velocity of a hit ball, L is a total length of a net thatreceives impact by the hit ball, which is calculated by the followingEquation (IV), h is a height of the net that receives impact by the hitball, which is calculated by the following Equation (V), R is a radiusof the ball to which hit is applied, and n is the number of twistsapplied to the synthetic fiber filament to prepare the synthetic fibercord,

L=12.007×N2×√{square root over (N1)}  (IV)

in the Equation (IV), N2 is an integer of 12, 17 or 24 as the number ofdistances (D) between the intersections of the net that receives impactby the hit ball, and N1 is an integer of 1,2 or 4 as the number ofintersections of the synthetic fiber cords to which the impact isapplied by the ball;

$\begin{matrix}{h = \frac{\left( {{Vo} \times \sin\; 0} \right)^{2}}{2 \times 9.81}} & (V)\end{matrix}$

in the Equation (V), Vo is an initial velocity of the hit ball, and θ isa ball hitting angle.

As shown in Table 1 above, it could be confirmed that, unlike theprotective net for golf manufactured in Example 1, the protective netfor golf manufactured in Comparative Example 1 where the distancesbetween the intersections (X) does not fall within the ranges ofEquations (II) and (III) had remarkably poor abrasion resistance of theprotective net.

Further, it could be confirmed that, unlike the protective net for golfmanufactured in Example 1, the protective net for golf manufactured inComparative Example 2 where the cord diameter did not satisfy Equation(I) and the cord material was changed to the HDPE had remarkably poorabrasion resistance and cutting strength.

EXAMPLE 2

Two strands of aramid filaments having a fineness of 3,000 denier wereplied and twisted to prepare aramid cords having a diameter of 0.7 mm.

Next, meshes were formed while crossing the aramid cords in a knotlesstype as shown in FIGS. 1 and 2 to manufacture a protective net forsoccer.

In this case, an distance between the intersections (X) of the aramidcords was adjusted to 137 mm.

The results of evaluating a cutting strength, a areal density, a rate ofhole size, and an abrasion resistance of the manufactured protective netfor soccer were shown in Table 2.

EXAMPLE 3

Two strands of aramid filaments having a fineness of 3,000 denier werePlied and twisted to prepare aramid cords having a diameter of 0.9 mm.

Next, meshes were formed while crossing the aramid cords in a knotlesstype as shown in FIGS. 1 and 2 to manufacture a protective net forbaseball.

In this case, an distance between the intersections (X) of the aramidcords was adjusted to 45 mm.

The results of evaluating a cutting strength, a areal density, a rate ofhole size, and an abrasion resistance of the manufactured protective netfor baseball were shown in Table 2.

EXAMPLE 4

Two strands of aramid filaments having a fineness of 3,000 denier wereplied and twisted to prepare aramid cords having a diameter of 0.85 mm.

Next, meshes were formed while crossing the aramid cords in a knotlesstype as shown in FIGS. 1 and 2 to manufacture a protective net fortennis.

In this case, an distance between the intersections (X) of the aramidcords was adjusted to 40 mm.

The results of evaluating a cutting strength, a areal density, a rate ofhole size, and an abrasion resistance of the manufactured protective netfor tennis were shown in Table 2.

EXAMPLE 5

Two strands of aramid filaments having a fineness of 3,000 denier werePlied and twisted to prepare aramid cords having a diameter of 0.4 mm.

Next, meshes were formed while crossing the aramid cords in a knotlesstype as shown in FIGS. 1 and 2 to manufacture a protective net forvolleyball.

In this case, an distance between the intersections (X) of the aramidcords was adjusted to 124 mm.

The results of evaluating a cutting strength, a areal density, a rate ofhole size, and an abrasion resistance of the manufactured protective netfor soccer were shown in Table 2.

TABLE 2 Category Example 2 Example 3 Example 4 Example 5 Equation(I)Maximum  0.84 mm  1.07 mm  1.03 mm  0.47 mm value Minimum  0.59 mm  0.75mm  0.73 mm  0.33 mm value Equation(II) 167.18 mm 54.96 mm 48.26 mm151.98 mm Equation(III) 128.97 mm 34.96 mm 30.71 mm  96.72 mm Cuttingstrength(daN) 114 114 114 114 Rate of hole size(%) 99.0 96.0 95.8 99.3Areal density(g/m²) 10 47 46 6 Abrasion resistance(hour) 31(Unbroken)31(Unbroken) 31(Unbroken) 31(Unbroken)

The physical properties of Table 1 and Table 2 were evaluated by thefollowing method:

Cutting Strength (daN)

The cutting strength was measured by collecting the mesh and fixing bothends thereof according to KS K ISO 1806, which is a mesh cutting loadmeasurement method of a fishing net.

Rate of Hole Size (%)

As shown in FIG. 3, the rate of hole size was calculated by substituting(i) an area (A) of the mesh and (ii) an area (B) into the followingEquation (VI), wherein the area (B) was obtained by multiplying a value(l1) adding a diameter (d) of the aramid cord to a transverse length(l2) of the mesh, and a value (h1) adding the diameter (d) of the aramidcord to a longitudinal length (h2) of the mesh:

$\begin{matrix}{{{Rate}\mspace{14mu}{of}\mspace{14mu}{hole}\mspace{14mu}{size}} = {\left( \frac{A}{B} \right) \times 100}} & ({VI})\end{matrix}$

Areal Density (g/m²)

The areal density was obtained by measuring a weight of the protectivenet with 1 m wide×1 m long.

Abrasion Resistance (Hours)

The abrasion resistance was expressed as a time required to damage theprotective net by allowing a golf ball rotating at 3,000 rpm to contactthe same position of the protective net after mounting the protectivenet to a rotational friction tester.

DESCRIPTION OF REFERENCE NUMERALS

C: synthetic fiber cord

d: diameter of synthetic fiber cord (C)

X: intersection between synthetic fiber cords (C)

A: area of mesh

h2: longitudinal length of mesh

l2: transverse length of mesh

h1: value adding diameter (d) of aramid cord to longitudinal length (h2)of mesh

l1: Value adding diameter of aramid cord to transverse length (l2) ofmesh

B: area multiplying h1 and l1

1: protective net for sports

2: ball

D: distance between intersections (X) of synthetic fiber cords

1. A protective net for sports characterized by forming meshes betweenintersections of synthetic fiber cords while the synthetic fiber cordshaving a form in which a plurality of synthetic fiber filaments areplied and twisted are crossed in a knotless type, wherein a diameter (d)of the synthetic fiber cord satisfies the following Equation (I), amaximum distance (D1) between the intersections adjacent to each othersatisfies the following Equation (II), and a minimum distance (D2)between the intersections adjacent to each other satisfies the followingEquation (III): $\begin{matrix}{{{Diameter}\mspace{14mu}(d)\mspace{14mu}{of}\mspace{14mu}{synthetic}\mspace{14mu}{fiber}\mspace{14mu}{cord}} = {N \times \sqrt{\frac{m \times {\sin^{2}(0)} \times \frac{1}{2}\left( {v_{0}^{2} - {9.81 \times h}} \right)}{\sigma \times ɛ \times L \times \pi}}}} & I \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 1} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = \frac{\pi\; R}{2\left( {1 + ɛ} \right)}} & {II} \\{{{Maximum}\mspace{14mu}{distance}\mspace{14mu}\left( {D\; 2} \right)\mspace{14mu}{between}\mspace{14mu}{adjacent}\mspace{14mu}{intersections}} = {\frac{\pi\; R}{2\left( {1 + ɛ} \right)} \times \left( \frac{n}{n + 4} \right)}} & {III}\end{matrix}$ in the Equations (I), (II) and (III), the units of each ofa diameter (d) of the synthetic fiber cord, a maximum distance (D1) anda minimum distance (D2) between the intersections adjacent to each otherare mm, m is a mass of a ball, N is a constant of 14.14214, c is anstrain of the synthetic fiber filament material, θ is ball hittingangle, σ is a stress of the synthetic fiber filament material, Vo is amaximum velocity of a hit ball, L is a total length of the net thatreceives impact by the hit ball, which is calculated by the followingEquation (IV), h is a height of the net that receives impact by the hitball, which is calculated by the following Equation (V), R is a radiusof the ball to which hit is applied, and n is the number of twistsapplied to the synthetic fiber filament to prepare the synthetic fibercord,L=12.007×N2×√N1   (IV) in the Equation (IV), N2 is an integer of 12, 17or 24 as the number of distances (D) between the intersections of thenet that receives impact by the hit ball, and N1 is an integer of 1,2 or4 as the number of intersections of the synthetic fiber cords to whichthe impact is applied by the ball; $\begin{matrix}{h = \frac{\left( {{Vo} \times \sin\; 0} \right)^{2}}{2 \times 9.81}} & (V)\end{matrix}$ in the Equation (V), Vo is an initial velocity of the hitball, and θ is a ball hitting angle.
 2. The protective net for sportsaccording to claim 1, wherein the synthetic fiber filament is an aramidfilament.
 3. The protective net for sports according to claim 1, whereinthe synthetic fiber cord includes an aramid filament.
 4. The protectivenet for sports according to claim 2, wherein the aramid filament has anstrain of 2% to 4% or less.
 5. The protective net for sports accordingto claim 1, wherein a areal density of the protective net for sports is1 g/m² to 100 g/m² or less.
 6. The protective net for sports accordingto claim 1, wherein a resin containing an ultraviolet stabilizer iscoated onto the synthetic fiber cord.
 7. The protective net for sportsaccording to claim 1, wherein a fabric having a narrow width is sewn toan end of the protective net for sports.
 8. The protective net forsports according to claim 1, wherein a cutting strength of theprotective net for sports is 114 daN or more.
 9. The protective net forsports according to claim 1, wherein a rate of hole size of theprotective net for sports is 90% or more by the following Equation (VI):$\begin{matrix}{{{Rate}\mspace{14mu}{of}\mspace{14mu}{hole}\mspace{14mu}{size}} = {\left( \frac{A}{B} \right) \times 100}} & ({VI})\end{matrix}$ in the Equation (VI), A is an area of the mesh, and B isan area obtained by multiplying a value (l1) adding a diameter (d) ofthe aramid cord to a transverse length (l2) of the mesh, and a value(h1) adding the diameter (d) of the aramid cord to a longitudinal length(h2) of the mesh.
 10. The protective net for sports according to claim1, wherein an abrasion resistance is 20 minutes or more, the abrasionresistance being a time required to damage the protective net byallowing a golf ball rotating at 3,000 rpm to contact the same positionof the protective net after mounting the protective net for sports to arotational friction tester.
 11. The protective net for sports accordingto claim 1, wherein the diameter (d) of the synthetic fiber cord is 0.85mm to 1.5 mm, the maximum distance (D1) of the intersections adjacent toeach other is 35 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 20 mm or more.
 12. Theprotective net for sports according to claim 1, wherein the diameter (d)of the synthetic fiber cord is 0.59 mm to 0.84 mm, the maximum distance(D1) of the intersections adjacent to each other is 140 mm or less, andthe minimum distance (D2) of the intersections adjacent to each other is135 mm or more.
 13. The protective net for sports according to claim 1,wherein the diameter (d) of the synthetic fiber cord is 0.75 mm to 1.07mm, the maximum distance (D1) of the intersections adjacent to eachother is 50 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 40 mm or more.
 14. Theprotective net for sports according to claim 1, wherein the diameter (d)of the synthetic fiber cord is 0.73 mm to 1.03 mm, the maximum distance(D1) of the intersections adjacent to each other is 42 mm or less, andthe minimum distance (D2) of the intersections adjacent to each other is38 mm or more.
 15. The protective net for sports according to claim 1,wherein the diameter (d) of the synthetic fiber cord is 0.33 mm to 0.47mm, the maximum distance (D1) of the intersections adjacent to eachother is 126 mm or less, and the minimum distance (D2) of theintersections adjacent to each other is 122 mm or more.
 16. A protectivenet for golf characterized by using the protective net for sports ofclaim
 11. 17. A protective net for soccer characterized by using theprotective net for sports of claim
 12. 18. A protective net for baseballcharacterized by using the protective net for sports of claim
 13. 19. Aprotective net for tennis characterized by using the protective net forsports of claim
 14. 20. A protective net for volleyball characterized byusing the protective net for sports of claim 15.